Human endothelial cells from umbilical veins, as well as adult arteries and veins will be studied: 1) to develop a quantitative and reproducible assay for cell migration in vitro by further standardizing a novel system of irradiated endothelial cell migration under agar, and 2) to characterize: a) Modulation of cell migration. The effect of growth factors, cellular factors, surface conditions, hormonal agents, oxygen tension, aging, homocysteine, endotoxin, cholesterol, triglyceride and sera from patients with certain clinical disorders such as: 1) hyperlipidemias, 2) renal failure, and 3) microangiopathic diseases will be assessed for effect on migration. b) The interaction of cell migration and proliferation. The relative roles of proliferation and migration in adjacent surface coverage will be determined using irradiated and nonirradiated cultures and autoradiographic techniques. The relationship, if any, between cell movement and subsequent proliferation will be investigated. c) The potential therapeutic role of pharmacologic agents. Drugs such as sulfinpyrazone, dipyridamole and aspirin will be investigated for their effects on normal and disordered cell migration as identified in antecedent studies.